The family of murdered teenager Stephen Lawrence will this week write to the Home Secretary to call for an inquiry into police wrongdoing to be reopened in light of fresh allegations of corruption.

It is alleged a bent Scotland Yard officer, who interviewed the suspects following the killing, had links to one of their gangster fathers.

Detective Sergeant John Davidson is said to have had close ties to Clifford Norris, whose son David Norris was arrested in the weeks after the 1993 racist attack.

Norris was convicted along with Gary Dobson in January this year of murder - 19 years after the crime - and both were sentenced to life at the Old Bailey. Norris was told he must serve at least 14 years and three months, while Dobson was given a minimum jail term of 15 years and two months. It is believed the pair had three or four accomplices, who remain at large.

Imran Khan, the Lawrence family solicitor, said: "Over the last few days we have had revelations that corruption may have infected the initial investigation into the murder of Stephen Lawrence."

He said it was unsuitable for the police or the Independent Police Complaints Commission (IPCC) to investigate the issue, and called for The Stephen Lawrence Inquiry to be reconvened. The subsequent Macpherson Report in February 1999 made 70 recommendations, many aimed at the institutionalised racism throughout the Metropolitan Police.

"The only way that we can move this forward is for the Home Secretary to reconvene the original inquiry, which couldn't deal with the issue of corruption back then because it didn't have the material on which to consider it," Mr Khan said. "The idea is for that to be looked into, not simply to root out corruption and to get to the bottom of it, but also it may have an impact on opening up lines of inquiry on the remaining individuals who are said to be responsible for Stephen's murder."

The announcement was made after a screening of a BBC Panorama special, Stephen Lawrence: A Time For Justice. Doreen Lawrence, Stephen's mother, and Stuart Lawrence, his brother answered questions after the hour-long documentary, which followed the family for the year up to Norris and Dobson's trial.

Mrs Lawrence told the audience at Bafta in Piccadilly in central London: "I think what came out this week has just proven what we have said for years. There had to be something. And what I couldn't understand was why Stephen, why his murder, was so difficult to solve. What was behind it all? And then when you hear about the relationship between the police and David Norris's father, then you begin to understand some of that."

Asked if she felt closure, Mrs Lawrence said: "I think closure's still a little bit out there for me. There's only two (in jail), so we've only had partial justice. I'm still trying to come to terms with the fact that we've got two behind bars."